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54 lines
1.5 KiB
Python
54 lines
1.5 KiB
Python
import hashlib
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import hmac
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from math import ceil
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BLOCK_SIZE = 32
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def extract(salt: bytes, ikm: bytes) -> bytes:
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h = hmac.new(salt, ikm, hashlib.sha256)
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return h.digest()
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def expand(L: int, prk: bytes, info: bytes) -> bytes:
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N: int = ceil(L / BLOCK_SIZE)
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bytes_written: int = 0
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okm: bytes = b""
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for i in range(1, N + 1):
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if i == 1:
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h = hmac.new(prk, info + bytes([1]), hashlib.sha256)
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T: bytes = h.digest()
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else:
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h = hmac.new(prk, T + info + bytes([i]), hashlib.sha256)
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T = h.digest()
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to_write = L - bytes_written
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if to_write > BLOCK_SIZE:
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to_write = BLOCK_SIZE
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okm += T[:to_write]
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bytes_written += to_write
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assert bytes_written == L
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return okm
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def extract_expand(L: int, key: bytes, salt: bytes, info: bytes) -> bytes:
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prk = extract(salt, key)
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return expand(L, prk, info)
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"""
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Copyright 2020 Chia Network Inc
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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"""
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